To be fair, comments _must_ be moderated or they turn into a cesspool in short order. A like-dislike count does not have that problem, though. And YouTube isn't removing the comments (yet).
Not every site is the same. News sites in the US turn off their comments because it's too difficult to moderate in the current political environment.
Hacker News isn't a content site, but is mainly created for commenting. It is less political than the news sites which removed comments. It can also handle the moderation more easily than news sites partly because it has a very strong ugliness and usability filter.